ok guys so im building a 350 with vortec heads and i was wondering how much fuel pressure i would need and if i would need to swap injectors.. i have a roller block from an 89 truck, and 906 vortec heads from a 98 1500.. the heads are stock, except for the springs and full roller rockers. i will be using GMPP intake with EGR blocked off, comp cams Extreme 4x4 X4258HR cam, flat top pistons, with a compression ratio of 9.76... i will be going to a true dual exhaust with a 3 wire o2 sensor..

cam specs:
Basic Operating RPM Range 1,000-5,000
Intake Duration at 050 inch Lift 206
Exhaust Duration at 050 inch Lift 210
Duration at 050 inch Lift 206 int./210 exh.
Advertised Intake Duration 258
Advertised Exhaust Duration 262
Advertised Duration 258 int./262 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.458 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.458 in.
Valve Lift with Factory Rocker Arm Ratio 0.458 int./0.458 exh.
Lobe Separation (degrees) 111
Intake Centerline 106

any help is appreciated..

 

What HP are you anticipating engine will develop? I will guess 300 HP?

You need to fuel it sufficiently to show 85% DC in your logs.

 

i'm estimating based on similar builds (although carb'd) ill see between 280-320 range... however i havent had much experience with tbi. what would your estimate be as far a fuel pressure and what would i need to do to attain this? will my stock injectors work? (350 from 89 3/4 ton suburban) or would i need to use 454 injectors? or is there an after market injector that i would need to look at? any guidance anyone can offer would be great, just my first time with tbi..

 

55 lbs injectors at 28 lbs FP supports 305 HP. I believe your injectors are 55 lbs.

 

I'm interested to see how this goes for you.

I have a similar setup. I have a 350 Vortec engine, 906 heads, slightly stiffer valve springs, a 1997 F car LT1 cam, shorty ceramic headers, GMPP Vortec TBI intake bored to 2". I will be using my EBL Flash in the truck.

Instead of the small injectors with high fuel pressure, I chose to use larger injectors at a lower pressure; I've got a 454 TBI with 80lb injectors mounted up.

My engine has been ready to go in since early August, I just need a weekend when the truck's not working (as it will be this weekend, helping ANOTHER friend move).

 

so with the 454 injectors, what fuel pressure are you attempting to run?

 

I'm starting with 15 psi. I have a Vortec truck in-tank pump.